Recent studies with the selective 5-HT1A antagonist WAY-100635 have confirmed a role for 5-HT1A receptors in learning and memory. Carli et. al. (Neuropharmacology (1999), 38(8), 1165-1173) demonstrated that WAY-100635 prevented the impairment of spatial learning caused by intrahippocampal injection of 3-[(R)-2-carboxypiperazin-4-yl]propyl-1-phosphonic acid (CPP), a competitive NMDA receptor antagonist, in a two-platform spatial discrimination task. Boast et al. (Neurobiol. Learn. Mem. (1999), 71(3) 259-271) found that WAY-100635 significantly reduced the cognitive impairment induced by the non-competitive NMDA antagonist MK801, as determined by the performance of rats trained on a delayed nonmatching to sample radial arm maze task. Menesis et. al. (Neurobiol. Learn. Mem. (1999), 71(2) 207-218) showed that post-training administration of WAY-100635 reversed the learning deficit induced by scopolamine, a cholinergic antagonist, in an autoshaping learning task. New and novel 5-HT1A antagonists would be useful for these and other uses.
In accordance with this invention, there is provided a group of novel 5-HT1A antagonists of the formula I: 
wherein
R1 is hydrogen, halo, cyano, carboxamido, carboalkoxy of two to six carbon atoms, trifluoromethyl, alkyl of 1 to 6 carbon atoms, alkoxy of 1 to 6 carbon atoms, alkanoyloxy of 2 to 6 carbon atoms, amino, mono- or di-alkylamino in which each alkyl group has 1 to 6 carbon atoms, alkanamido of 2 to 6 carbon atoms, or alkanesulfonamido of 1 to 6 carbon atoms;
Xxe2x80x94Yxe2x80x94Z is Nxe2x95x90C(R2)xe2x80x94O, Nxe2x95x90C(R2)xe2x80x94NH or NHxe2x80x94C(R2)xe2x95x90CH;
R2 is hydrogen, halo, trifluoromethyl, amino, mono- or di-alkylamino in which each alkyl group has 1 to 6 carbon atoms, alkoxy of one to six carbon atoms or alkyl of one to six carbon atoms; and
R3 is phenyl, naphthyl, anthracyl, phenanthryl, pyridyl, pyrimidyl, triazinyl, thienyl, furyl, pyrrolyl, pyrazolyl, indolyl, imidazolyl, benzofuryl, benzothienyl, oxazolyl, or thiazolyl, each optionally substituted with from one to three substituents selected from hydroxy, halo, trifluoromethyl, cyano, amino, mono- or di-alkylamino in which each alkyl group has 1 to 6 carbon atoms, alkoxy of one to six carbon atoms and alkyl of one to six carbon atoms;
or a pharmaceutically acceptable salt thereof.
In some embodiments of the present invention Xxe2x80x94Yxe2x80x94Z is Nxe2x95x90C(R2)xe2x80x94O.
R1 is preferably hydrogen, halo, trifluoromethyl, alkyl of 1 to 6 carbon atoms, alkoxy of 1 to 6 carbon atoms, amino, mono- or di-alkylamino in which each alkyl group has 1 to 6 carbon atoms. In more preferred embodiments, R1 is hydrogen, trifluoromethyl, alkyl of one to six carbon atoms or alkoxy of one to six carbon atoms.
In some embodiments of the present invention R2 is preferably hydrogen, trifluoromethyl, amino, mono- or dialkylamino in which each alkyl group has one to six carbon atoms, or alkyl of 1 to 6 carbon atoms, R2 is more preferably hydrogen, trifluoromethyl, or alkyl of one to six carbon atoms. R2 is still more preferably hydrogen or alkyl of one to six carbon atoms and still more preferably alkyl from 1 to 3 carbon atoms.
In other embodiments of the present invention R3 is phenyl, naphthyl, pyridyl, pyrimidyl, thienyl, furyl, pyrrolyl, pyrazolyl, indolyl, imidazolyl, benzofuryl, or benzothienyl, each optionally substituted with from one to three substituents selected from hydroxy, halo, trifluoromethyl, cyano, amino, mono- or di-alkylamino in which each alkyl group has 1 to 6 carbon atoms, alkoxy of one to six carbon atoms and alkyl of one to six carbon atoms. R3 is more preferably phenyl, naphthyl, pyridyl, pyrrolyl, indolyl, or benzothienyl, each optionally substituted with from one to three substituents selected from halo, trifluoromethyl, cyano, alkoxy of one to six carbon atoms and alkyl of one to six carbon atoms R3 is preferably phenyl or naphthyl, each optionally substituted with from one to three substituents selected from halo, trifluoromethyl, cyano, alkoxy of one to six carbon atoms and alkyl of one to six carbon atoms.
Still more preferred compounds are those in which R1 is hydrogen, halo, trifluoromethyl, alkyl of one to six carbon atoms, alkoxy of one to six carbon atoms, amino, mono- or di-alkylamino in which each alkyl group has one to six carbon atoms; R2 is hydrogen, trifluoromethyl, amino, mono- or di-alkylamino in which each alkyl group has one to six carbon atoms, or alkyl of one to six carbon atom; and R3 is phenyl, naphthyl, pyridyl, pyrimidyl, thienyl, furyl, pyrrolyl, pyrazolyl, indolyl, imidazolyl, benzofuryl, or benzothienyl, each optionally substituted with from one to three substituents selected from hydroxy, halo, trifluoromethyl, cyano, amino, mono- or di-alkylamino in which each alkyl group has 1 to 6 carbon atoms, alkoxy of one to six carbon atoms and alkyl of one to six carbon atoms.
Most preferred are those in which R1 is hydrogen, halo, trifluoromethyl, alkyl of one to six carbon atoms or alkoxy of one to six carbon atoms; R2 is hydrogen, trifluoromethyl or alkyl of one to six carbon atom; and R3 is phenyl, naphthyl, pyridyl, pyrrolyl, indolyl, or benzothienyl, each optionally substituted with from one to three substituents selected from halo, trifluoromethyl, cyano, alkoxy of one to six carbon atoms and alkyl of one to six carbon atoms.
This invention relates to both the R and S stereoisomers of the 8-aminomethyl-7,8-dihydro-1,6,9-trioxa-3-aza-cyclopenta[a]naphthalene, as well as to mixtures of the R and S stereoisomers. Throughout this application, the name of the product of this invention, where the absolute configuration of the 8-aminomethyl-7,8-dihydro-1,6,9-trioxa-3-aza-cyclopenta[a]naphthalene is not indicated, is intended to embrace the individual R and S enantiomers as well as mixtures of the two. In some preferred embodiments of the present invention the S isomer is preferred.
Where a stereoisomer is preferred, it may, in some embodiments be provided substantially free of the corresponding enantiomer. Thus, an enantiomer substantially free of the corresponding enantiomer refers to a compound which is isolated or separated via separation techniques or prepared free of the corresponding enantiomer. Substantially free, as used herein means that the compound is made up of a significantly greater proportion of one stereoisomer. In preferred embodiments the compound is made up of at least about 90% by weight of a preferred stereoisomer. In other embodiments of the invention, the compound is made up of at least about 99% by weight of a preferred stereoisomer. Preferred stereoisomers may be isolated from racemic mixtures by any method known to those skilled in the art, including high performance liquid chromatography (HPLC) and the formation and crystallization of chiral salts or by methods described herein. See, for example, Jacques, et. al., Enantiomers, Racemates and Resolutions (Wiley Interscience, New York, 1981); Wilen, S. H., et. al., Tetrahedron 33:2725 (1977); Eliel, E. L. Stereochemistry of Carbon Compounds (McGraw-Hill, N.Y., 1962); Wilen, S. H. Tables of Resolving Agents and Optical Resolutions p. 268 (E. L. Eliel, Ed., Univ. of Notre Dame Press, Notre Dame, Ind. 1972).
Alkyl as used herein refers to an aliphatic hydrocarbon chain and includes straight and branched chains such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-pentyl, isopentyl, neo-pentyl, n-hexyl, and isohexyl. Lower alkyl refers to alkyl having 1 to 3 carbon atoms.
Alkanamido as used herein refers to the group Rxe2x80x94C(xe2x95x90O)xe2x80x94NHxe2x80x94 where R is an alkyl group of 1 to 5 carbon atoms.
Alkanoyloxy as used herein refers to the group Rxe2x80x94C(xe2x95x90O)xe2x80x94Oxe2x80x94 where R is an alkyl group of 1 to 5 carbon atoms.
Alkanesulfonamido as used herein refers to the group Rxe2x80x94S(O)2xe2x80x94NHxe2x80x94 where R is an alkyl group of 1 to 6 carbon atoms.
Alkoxy as used herein refers to the group Rxe2x80x94Oxe2x80x94 where R is an alkyl group of 1 to 6 carbon atoms.
Carboxamido, as used herein refers to the group xe2x80x94COxe2x80x94NH2.
Carboalkoxy as used herein refers to the group Rxe2x80x94Oxe2x80x94C(xe2x95x90O)xe2x80x94 where R is an alkyl group of 1 to 5 carbon atoms.
Halogen (or halo) as used herein refers to chlorine, bromine, fluorine and iodine.
Pharmaceutically acceptable salts are those derived from such organic and inorganic acids as: acetic, lactic, citric, cinnamic, tartaric, succinic, fumaric, maleic, malonic, mandelic, malic, oxalic, propionic, hydrochloric, hydrobromic, phosphoric, nitric, sulfuric, glycolic, pyruvic, methanesulfonic, ethanesulfonic, toluenesulfonic, salicylic, benzoic, and similarly known acceptable acids.
Specific compounds of Formula I include:
8-{[2-Methyl-7,8-dihydro[1,4]dioxino[2,3-g][1,3]benzoxazol-8-yl]methyl}-3-phenyl-8-azabicyclo[3.2.1]octan-3-ol;
8-{[2-Methyl-7,8-dihydro[1,4]dioxino[2,3-g][1,3]benzoxazol-8-yl]methyl}-3-[3-(trifluoromethyl)phenyl]-8-azabicyclo[3.2.1]octan-3-ol;
8-{[2-Methyl-7,8-dihydro[1,4]dioxino[2,3-g][1,3]benzoxazol-8-yl]methyl}-3-(2-naphthyl)-8-azabicyclo[3.2.1]octan-3-ol.
Compounds of the present invention are prepared in accordance with the following schemes and specific examples. Variables used are as defined for Formula I unless otherwise noted.
The 8-azabicyclylmethyl-7,8-dihydro-1,6,9-trioxa-3-aza-cyclopenta-[a]-naphthalenes of the invention are prepared as illustrated in Scheme I, below. Specifically, the appropriately substituted nitroguaiacol is alkylated with allyl bromide in the presence of a suitable base such as sodium hydride and then demethylated by a reagent such as sodium hydroxide. The resulting 4-nitro-2-allyloxyphenol is then alkylated with glycidyl tosylate or an epihalohydrin in the presence of a base such as sodium hydride and heated in a high boiling solvent such as mesitylene or xylene to effect both rearrangement of the allyl group and cyclization of the dioxan ring. The resulting primary alcohol is converted to the tosylate by reaction with p-toluenesulfonyl chloride in the presence of a tertiary amine or pyridine or alternatively to a halide by reaction with carbon tetrabromide or carbon tetrachloride in combination with triphenylphosphine. The allyl side chain is then isomerized by treatment with catalytic bis-acetonitrile palladium (II) chloride in refluxing methylene chloride or benzene and the nitro group reduced to the aniline with a suitable reducing agent such as tin (II) chloride. The aniline is then acylated with the appropriate acyl halide or anhydride and the olefin cleaved to the corresponding o-amidobenzaldehyde by treatment with catalytic osmium tetroxide in the presence of sodium periodate. The aldehyde is converted to the phenol by treatment with meta-chloroperoxybenzoic acid in a Baeyer-Villager reaction and cyclization to the 7,8-dihydro-1,6,9-trioxa-3-aza-cyclopenta[a]naphthalene is effected by treatment at reflux with an appropriate dehydrating agent such as an ortho ester. Replacement of the tosylate or halide with the appropriately substituted azabicycle in some high boiling solvent such as dimethyl sulfoxide gives the title compounds of the invention. 
Alternatively, as shown in Scheme II, the aniline produced by the tin (II) chloride reduction described above may be protected by a suitable protecting group such as carbobenzoxy (Cbz) before the olefin is cleaved to the aldehyde by treatment with osmium tetroxide/sodium periodate and the aldehyde converted to a phenol by the Baeyer-Villager procedure. Deprotection by treatment with hydrogen over palladium on carbon gives the o-aminophenol, which is cyclized to the 7,8-dihydro-1,6,9-trioxa-3-aza-cyclopenta[a]naphthalene by treatment with the appropriate ortho ester, carboxylic acid or anhydride. Treatment of the o-aminophenol with cyanogen bromide or chloride or a suitably substituted carbamoyl chloride leads to compounds of the invention in which R2 is amino. Treatment of the o-aminophenol with carbonyl diimidazole gives the oxazolone which leads to compounds of the invention in which R2 is halo via treatment with an inorganic anhydride such as phosphoryl chloride or bromide, or to compounds of the invention in which R2 is alkoxy by treatment with the appropriate alkylating agent. Replacement of the tosylate with the appropriately substituted azabicycle as above gives the title compounds of the invention. 
Compounds of the invention in which Xxe2x80x94Yxe2x80x94Z is Nxe2x95x90C(R2)xe2x80x94O, R1 is hydrogen and R2 is alkyl are most conveniently prepared according to scheme III below. The appropriate 2xe2x80x2,3xe2x80x2,4xe2x80x2-trihydroxyacylphenone is regioselectively alkylated with glycidyl tosylate or an epihalohydrin in the presence of a base such as sodium carbonate to give the corresponding 7-acyl-8-hydroxybenzodioxan-2-methanol. Following conversion of the ketone to the oxime by reaction with hydroxylamine hydrochloride and sodium acetate, cyclization to the oxazole is effected by treatment with phosphoryl chloride in the appropriate dimethylalkanoic acid amide. The resulting 7,8-dihydro-1,6,9-trioxa-3-aza-cyclopenta[a]naphthalene-8-methanol is converted to the tosylate by treatment with p-toluenesulfonyl chloride in pyridine and combined with the appropriate azabicycles as described to give the title compounds of the invention. 
2,3-dihydro-7H-[1,4]dioxino[2,3-e]indoles of Formula I are prepared as described in Scheme IV. Specifically, the allyl side chain of the tosylate is cleaved to the aldehyde by treatment with ozone at low temperature, followed by work-up with a tertiary base such as diisopropylethylamine or triethylamine, or by treatment with catalytic osmium tetroxide and sodium periodate. Reduction of the nitro group with hydrogen over platinum oxide leads directly to formation of the indole in which R2 is hydrogen. Alternatively, the aldehyde may be treated with an appropriate alkyl Grignard reagent or with trifluoromethyl trimethylsilane in the presence of cesium fluoride, then oxidized to a ketone with a suitable oxidant such as pyridinium chlorochromate (PCC) or the Swern reagent and reduced with hydrogen over platinum oxide to give the indoles in which R2 is alkyl or trifluoromethyl. Replacement of the tosylate or halide with the appropriately substituted azabicycle in some high boiling solvent such as dimethyl sulfoxide gives the title compounds of the invention. 
The compounds of the invention in which Xxe2x80x94Yxe2x80x94Z is NHxe2x80x94C(R2)xe2x95x90CH and R2 is a halogen such as chlorine or bromine are prepared from the nitroaldehyde described by the procedure of Scheme V. The aldehyde is oxidized to the phenylacetic acid by a suitable oxidant such as the Jones reagent (CrO3, H2SO4 in acetone) and then the nitro group is reduced to the amine by treatment with hydrogen in the presence of a catalyst such as palladium on carbon. Cyclization to the oxindole is effected by treatment with acid and the oxindole converted to the haloindole such as bromo or chloroindole via treatment with the appropriate carbon tetrahalide and triphenylphosphine in a solvent such as methylene chloride. Replacement of the tosylate with the appropriately substituted azabicycle in some high boiling solvent such as dimethyl sulfoxide gives the title compounds of the invention. 
Such compounds of the invention may alternatively be prepared from the 7-nitro-8-allyl benzodioxan derived from the Claisen rearrangement by the procedure of Scheme VI. The alcohol is converted to the tosylate or halide as described above and the double bond is isomerized by treatment with bis-acetonitrile palladium (II) chloride in refluxing methylene chloride or benzene. Cleavage of the olefin with ozone or osmium tetroxide/periodate gives the o-nitrobenzaldehyde, which is condensed with the appropriate nitroalkane in the presence of a suitable base catalyst to yield the corresponding o,xcex2-dinitrostyrene. Reduction of both nitro groups with hydrogen over palladium on carbon is accompanied by cyclization to form the indole. Replacement of the tosylate with the appropriately substituted azbicycle as above, gives the title compounds of the invention. 
Compounds of the invention in which Xxe2x80x94Yxe2x80x94Z is NHxe2x80x94C(R2)xe2x95x90CH and R2 is methyl may be most conveniently prepared from the 7-nitro-8-allyl benzodioxan (6) described above by the procedure of Scheme VII. The nitro group is reduced with tin (II) chloride dihydrate in refluxing ethyl acetate to produce and cyclization to the 2-methylindole effected by several days"" treatment with catalytic bis-acetonitrile (II) chloride, lithium chloride and 1,4-benzoquinone at room temperature in tetrahydrofuran. Replacement of the tosylate with the appropriately substituted azabicycle as above gives the title compounds of the invention. 
Compounds of the invention where Xxe2x80x94Yxe2x80x94Z is Nxe2x95x90C(R2)xe2x80x94NH are prepared as illustrated in Scheme VII below. Specifically, the allyl side chain is isomerized by treatment with catalytic bis-acetonitrile palladium (II) chloride in refluxing methylene chloride or benzene and cleaved to the corresponding o-nitrobenzaldehyde by treatment with ozone followed by diisopropylethylamine or by catalytic osmium tetroxide in the presence of sodium periodate. The aldehyde is oxidized to the o-nitrobenzoic acid by a suitable oxidant such as chromium trioxide (Jones"" oxidation) or sodium chlorite and the acid converted to the o-nitroaniline with diphenylphosphoryl azide (DPPA) in the presence of a
tertiary base such as diisopropylethylamine (Curtius reaction). Reduction of the resulting nitroaniline to the diamine is performed with hydrogen and palladium on carbon and cyclization is achieved by treatment at reflux with the appropriate carboxylic acid. Refluxing the diamine dihydrochloride in higher boiling carboxylic acids occasionally causes replacement of a tosylate group with a chloride. Replacement of the tosylate or halide with the appropriately substituted azabicycle in some high boiling point solvent such as dimethylsulfoxide give the title compound of the invention. 
Treatment of the diamine described in Scheme VIII, above, with cyanogen bromide or chloride or a suitably substituted carbamoyl chloride leads to compounds of the invention in which R2 is amino. Treatment of the diamine with carbonyl diimidazole gives the imidazolone which leads to compounds of the invention in which Xxe2x80x94Yxe2x80x94Z is Nxe2x95x90C(R2)xe2x80x94NH and R2 is halo via treatment with an inorganic anhydride such as phosphoryl chloride or bromide, or to compounds of the invention in which Nxe2x95x90C(R2)xe2x80x94NH and R2 is alkoxy by treatment with the appropriate alkylating agent. Replacement of the tosylate with the appropriately substituted azabicycle as above gives the title compounds of the invention.
Compounds of the invention in which Nxe2x95x90C(R2)xe2x80x94NH and R2 is trifluoromethyl may also be conveniently prepared from the nitroaniline described above by the procedure illustrated below in Scheme IX. The nitroaniline is treated with trifluoroacetic anhydride in the presence of a suitable tertiary base such as diisopropylethylamine to yield the o-nitrophenyl trifluoroacetamide. This intermediate is reduced to the o-anilino trifluoroacetamide by treatment with hydrogen over palladium on carbon and cyclized to the trifluoromethylimidazole in refluxing trifluoroacetic acid. Replacement of the tosylate with the appropriately substituted azabicycle as above gives the title compounds of the invention. 
The azabicycles appropriate to the invention are known compounds or they may be prepared by the following procedure. Thus, tropinone is converted to the corresponding N-benzyltropinone by first reacting with 1-chloroethyl chloroformate in hot methylene chloride or 1,2-dichloroethane (DCE), treatment of the resulting carbamate with hot methanol, ethanol or similar alcohols and finally treatment with benzyl bromide, benzyl chloride or other benzylating agents known to the skilled artisan in a solvent such as tetrahydrofuran, benzene, N,N-dimethylformamide, or methylene chloride in the presence of a tertiary amine base. Benzyltropinone may be converted to the tropinol by reaction with an aryl lithium, aryl Grignard, or other aryl organometallics in a suitable solvent such as tetrahydrofuran or ether at xe2x88x9278xc2x0 C., followed by warming to room temperature. The aryl organometallics used may be obtained from aryl halides as shown below. Aryl halides may be obtained commercially or by standard routes known to the skilled artisan. Only the product of exo addition is isolated as shown in the scheme below. The benzyl group may be removed via transfer hydrogenation over a precious metal catalyst such as palladium on carbon using formamide/methanol as the source of hydrogen. 
The guaiacols and 2xe2x80x2,3xe2x80x2,4xe2x80x2-trihydroxyacylphenones appropriate to the above chemistry are known compounds or can be prepared by one schooled in the art. The compounds of the invention may be resolved into their enantiomers by conventional methods or, preferably, the individual enantiomers may be prepared directly by substitution of (2R)-(xe2x88x92)-glycidyl 3-nitrobenzenesulfonate or tosylate (for the S benzodioxan methanamine) or (2S)-(+)-glycidyl 3-nitrobenzenesulfonate or tosylate (for the R enantiomer) in place of epihalohydrin or racemic glycidyl tosylate in the procedures above.
The 5-HT1A affinity of compounds of this invention was established in accordance with standard pharmaceutically accepted test procedures with representative compounds as follows.
High affinity for the serotonin 5-HT1A receptor was established by testing the claimed compound""s ability to displace [3H] 8-OH-DPAT (dipropylaminotetralin) from the 5-HT1A serotonin receptor following a modification of the procedure of Hall et. al., J. Neurochem. 44, 1685 (1985) which utilizes CHO cells stably transfected with human 5-HT1A receptors. The 5-HT1A affinities for the compounds of the invention are reported below as Ki""s.
Antagonist activity at 5-HT1A receptors was established by using a 35S-GTPxcex3S binding assay similar to that used by Lazareno and Birdsall (Br. J. Pharmacol. 109: 1120, 1993), in which the test compound""s ability to affect the binding of 3S-GTPxcex3S to membranes containing cloned human 5-HT1A receptors was determined. Agonists produce an increase in binding whereas antagonists produce no increase but rather reverse the effects of the standard agonist 8-OH-DPAT. The test compound""s maximum inhibitory effect is represented as the Imax, while its potency is defined by the IC50.
The results of the two standard experimental test procedures described in the preceding two paragraphs were as follows:
The compounds of this invention have potent affinity for and antagonist activity at brain 5-HT1A serotonin receptors. The compounds of the invention are thus exceedingly interesting for the treatment of cognitive dysfunction such as is associated with mild cognitive impairment (MCI) Alzheimer""s disease and other dementias including Lewy Body, vascular, and post stroke dementias. Cognitive dysfunction associated with surgical procedures, traumatic brain injury or stroke may also be treated in accordance with the present invention. Further, compounds of the present invention may be useful for the treatment of diseases in which cognitive dysfunction is a co-morbidity such as, for example, Parkinson""s disease, autism and attention deficit disorders.
Compounds of the present invention are also useful for treating cognitive deficits due to CNS disorders such as schizophrenia, (and other psychotic disorders such as paranoia and mano-depressive illness). The compounds are also useful for the treatment of disorders related to excessive serotonergic stimulation such as anxiety (e.g. generalized anxiety disorders, panic attacks, and obsessive compulsive disorders), aggression and stress. In addition, compounds of the present invention may be useful for the treatment of various physiological conditions such as Tourette""s syndrome, migraine, autism, attention deficit disorders and hyperactivity disorders, sleep disorders, social phobias, pain, thermoregulatory disorders, endocrine disorders, urinary incontinence, vasospasm, stroke, eating disorders such as for example obesity, anorexia and bulimia, sexual dysfunction, and the treatment of alcohol, drug and nicotine withdrawal which are known to be, at least in part, under serotonergic influence. Finally, recent clinical trials employing drug mixtures (e.g. fluoxetine and pindolol) have demonstrated a more rapid onset of antidepressant efficacy for a treatment combining SSRI (serotonin selective reuptake inhibitor) activity and 5HT1A antagonism (Blier and Bergeron, 1995; F Artigas, et. al., 1996, M. B. Tome et. al., 1997). The compounds of the invention are thus interesting and useful as augmentation therapy in the treatment of depressive illness. Compounds of the present invention may thus be provided in combination with an antidepressant amount of a serotonin selective reuptake inhibitor to increase the onset of antidepressant efficacy. Such serotonin selective reuptake inhibitor includes, but is not limited to, fluoxetine, venlafaxine, citalopram, duloxetine, sertraline, paroxetine, fluvoxamine, nefazodone, and mirtazapine, and metabolites thereof.
Thus the present invention provides methods of treating, preventing, inhibiting or alleviating each of the maladies listed above in a mammal, preferably in a human, the methods comprising providing a pharmaceutically effective amount of a compound of this invention to the mammal in need thereof.
The present invention also provides methods of augmenting the treatment of depression by providing a mammal, preferably a human, with an antidepressant amount of a serotonin selective reuptake inhibitor (such as fluoxetine, venlafaxine, citalopram, duloxetine, sertraline, paroxetine, fluvoxamine, nefazodone, and mirtazapine, and metabolites thereof) and an amount of a compound of Formula I sufficient to hasten the onset of antidepressant efficacy.
Also encompassed by the present invention are pharmaceutical compositions for treating or controlling disease states or conditions of the central nervous system comprising at least one compound of Formula I, mixtures thereof, and or pharmaceutical salts thereof, and a pharmaceutically acceptable carrier therefore. Such compositions are prepared in accordance with acceptable pharmaceutical procedures, such as described in Remingtons Pharmaceutical Sciences, 17th edition, ed. Alfonoso R. Gennaro, Mack Publishing Company, Easton, Pa. (1985). Pharmaceutically acceptable carriers are those that are compatible with the other ingredients in the formulation and biologically acceptable. Pharmaceutical compositions of the present invention may further comprise a serotonin selective reuptake inhibitor such as, but not limited to fluoxetine, venlafaxine, citalopram, duloxetine, sertraline, paroxetine, fluvoxamine, nefazodone, and mirtazapine, and metabolites thereof.
The compounds of this invention may be administered orally or parenterally, neat or in combination with conventional pharmaceutical carriers. Applicable solid carriers can include one or more substances which may also act as flavoring agents, lubricants, solubilizers, suspending agents, fillers, glidants, compression aids, binders or tablet-disintegrating agents or an encapsulating material. In powders, the carrier is a finely divided solid which is in admixture with the finely divided active ingredient. In tablets, the active ingredient is mixed with a carrier having the necessary compression properties in suitable proportions and compacted in the shape and size desired. The powders and tablets preferably contain up to 99% of the active ingredient. Suitable solid carriers include, for example, calcium phosphate, magnesium stearate, talc, sugars, lactose, dextrin, starch, gelatin, cellulose, methyl cellulose, sodium carboxymethyl cellulose, polyvinylpyrrolidine, low melting waxes and ion exchange resins.
Liquid carriers may be used in preparing solutions, suspensions, emulsions, syrups and elixirs. The active ingredient of this invention can be dissolved or suspended in a pharmaceutically acceptable liquid carrier such as water, an organic solvent, a mixture of both or pharmaceutically acceptable oils or fat. The liquid carrier can contain other suitable pharmaceutical additives such as solubilizers, emulsifiers, buffers, preservatives, sweeteners, flavoring agents, suspending agents, thickening agents, colors, viscosity regulators, stabilizers or osmo-regulators. Suitable examples of liquid carriers for oral and parenteral administration include water (particularly containing additives as above e.g. cellulose derivatives, preferably sodium carboxymethyl cellulose solution), alcohols (including monohydric alcohols and polyhydric alcohols e.g. glycols) and their derivatives, and oils (e.g. fractionated coconut oil and arachis oil). For parenteral administration the carrier can also be an oily ester such as ethyl oleate and isopropyl myristate. Sterile liquid carriers are used in sterile liquid form compositions for parenteral administration.
Liquid pharmaceutical compositions which are sterile solutions or suspensions can be utilized by, for example, intramuscular, intraperitoneal or subcutaneous injection. Sterile solutions can also be administered intravenously. Oral administration may be either liquid or solid composition form.
Preferably the pharmaceutical composition is in unit dosage form, e.g. as tablets, capsules, powders, solutions, suspensions, emulsions, granules, or suppositories. In such form, the composition is sub-divided in unit dose containing appropriate quantities of the active ingredient; the unit dosage forms can be packaged compositions, for example packeted powders, vials, ampoules, prefilled syringes or sachets containing liquids. The unit dosage form can be, for example, a capsule or tablet itself, or it can be the appropriate number of any such compositions in package form.
The amount provided to a patient will vary depending upon what is being administered, the purpose of the administration, such as prophylaxis or therapy, and the state of the patient, the manner of administration, and the like. In therapeutic applications, compounds of the present invention are provided to a patient already suffering from a disease in an amount sufficient to cure or at least partially ameliorate the symptoms of the disease and its complications. An amount adequate to accomplish this is defined as a xe2x80x9ctherapeutically effective amount.xe2x80x9d The dosage to be used in the treatment of a specific case must be subjectively determined by the attending physician. The variables involved include the specific condition and the size, age and response pattern of the patient. Generally, a starting dose is about 5 mg per day with gradual increase in the daily dose to about 150 mg per day, to provide the desired dosage level in the human.
Provide as used herein means either directly administering a compound or composition of the present invention, or administering a prodrug, derivative or analog which will form an equivalent amount of the active compound or substance within the body.
The present invention includes prodrugs of compounds of Formula I. xe2x80x9cProdrugxe2x80x9d, as used herein means a compound which is convertible in vivo by metabolic means (e.g. by hydrolysis) to a compound of Formula I. Various forms of prodrugs are known in the art, for example, as discussed in Bundgaard, (ed.), Design of Prodrugs, Elsevier (1985); Widder, et. al. (ed.), Methods in Enzymology, vol. 4, Academic Press (1985); Krogsgaard-Larsen, et. al., (ed). xe2x80x9cDesign and Application of Prodrugs, Textbook of Drug Design and Development, Chapter 5, 113-191 (1991), Bundgaard, et. al., Journal of Drug Deliver Reviews, 8:1-38(1992), Bundgaard, J. of Pharmaceutical Sciences, 77:285 et seq. (1988); and Higuchi and Stella (eds.) Prodrugs as Novel Drug Delivery Systems, American Chemical Society (1975).
The following examples illustrate the production of representative compounds of this invention.